Backup Volume Bitmap Tracking via Modification Time
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Solution Overview
Problem
Existing backup systems fail to accurately track and accommodate the resizing or recreation of volumes at the block-level, leading to incomplete or incorrect backups due to the reuse of minor numbers and lack of proper bitmap management.
Innovation Solution
The implementation of a system that utilizes a pseudo device layer between the file system and device layers, employing record ID or modification time as additional indices to correlate minor numbers with bitmaps, ensuring accurate tracking and updating of bitmaps during volume resizing or recreation, thereby ensuring proper backup operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional bitmap tracking is used for block-level backups, then backup speed is improved, but reliability deteriorates when volumes are resized or recreated due to minor number reuse
Solution Approach 1:
The patent introduces a volume identifier (such as volume serial number, UUID, or other unique identifiers) as an intermediary layer between the bitmap tracking mechanism and the volume device. This intermediary ensures that even when minor numbers are reused during volume recreation, the bitmap remains correctly associated with the specific volume instance through the unique volume identifier, thereby maintaining backup accuracy without sacrificing the efficiency of bitmap-based tracking.
2Adaptability or versatility
If volume manager allows flexible volume deletion and recreation, then adaptability is improved, but device complexity increases due to need to track and report major/minor number repetitions
Solution Approach 1:
The volume identifier serves as a mediator that simplifies the tracking mechanism. Instead of monitoring complex major/minor number assignments and detecting repetitions, the system directly uses the unique volume identifier to associate bitmaps with volumes. This approach maintains the flexibility of volume deletion and recreation while significantly reducing the complexity of the tracking system.
Solution Approach 2:
The volume manager inherently provides volume identifiers (such as volume serial numbers or UUIDs) that automatically serve the tracking purpose. The backup system leverages this self-provided identifier without needing to implement its own complex tracking infrastructure, allowing volume manager flexibility to be maintained while reducing overall system complexity.
3Manufacturing precision
If bitmap length is made proportional to volume size, then manufacturing precision is improved for tracking writes, but loss of information increases when volume size changes are not tracked
Solution Approach 1:
The volume identifier acts as a mediator that links the bitmap to the specific volume instance. When a volume is resized or recreated, the system detects the change by comparing volume identifiers and adjusts the bitmap length accordingly. This ensures that the bitmap maintains precise write tracking capability (proportional to current volume size) while preventing information loss that would occur if volume changes were not detected.
Data Source
AI summary
This disclosure relates to a method, article of manufacture, and apparatus for backing up data. In some embodiments, this includes a backup server locating one or more instances of data associated with a list of identifiers, wherein each instance of data comprises one or more target volumes and associated journal volume; the enablement of replication; and replication.